An item with an integral porous or perforated plate, or with slits on the inside of a double wall.
NSN 6645-01-021-5727
NSN 6220-01-474-5682
NSN 5895-00-996-1660
NSN 6150-00-518-2125
NSN 6130-01-394-4986
NSN 5925-00-013-1258
NSN 6145-00-155-5297
NSN 6320-00-790-4844
NSN 5925-00-206-3580
NSN 6650-01-430-7130
NSN 5990-01-514-8030
NSN 5930-01-507-0793